Insect of the Week (Aug 19) - Doppelgangers: Giant water bug vs Cockroach

Years ago, I was walking home from the University of Alberta campus on a September evening, watching the ground, as entomologists are wont to do, when I saw a huge insect on its back on the sidewalk. It was just off of a major crosswalk under a streetlight. Upon a quick glance, I knew it was one of two things: a giant water bug or a cockroach. Either way, I needed it for my collection, so I carefully collected it using the only container I had on hand. I say that I “carefully collected” it, because water bugs are known for their painful bite and I did not want to take any risks. From inside the container, it was clear that I had scooped up a water bug.

Giant water bugs (Lethocerus americanus) are true bugs (Hemiptera) that belong to the family Belostomatidae.  There are over 150 species of water bugs in the Belostomatidae, but most are quite large (> 2 cm). Belostomatids are usually found in ponds, lakes, or slow moving rivers and streams. They spend most of their time in the water, but disperse between bodies of water by flying (except in species that have reduced wings and are flightless), at which time they may be found around streetlights or porchlights. They are predators of other insects, small fish, snails, amphibians, and other animals that they encounter in the water. Giant water bugs use their forelegs to capture prey and then use their long beak-like proboscis to feed on their prey. First, they inject enzymes into their prey that breakdown prey tissues into a liquid. Then they feast on a liquid lunch by sucking their victim dry. Their bite can be very painful. These ‘toe-biters’ are best avoided, but they are important beneficial insects in aquatic ecosystems.

Giant water bugs can be easily mistaken for adult cockroaches (especially the American cockroach, Periplaneta americana, Blattodea: Blattidae). Both water bugs and cockroaches havelarge, oval shaped bodies that are usually brown coloured. A casual glance or quick encounter with either may lead to a case of mistaken identity. But, upon closer examination, some key differences are easy to see:

1. Cockroaches have long, obvious antennae. Water bugs do not appear to have antennae unless closely examined.
2. The head and eyes of water bugs are visible from above. The head and eyes of cockroaches are hidden underneath the pronotum.
3. Cockroaches have spiny legs evolved for running and quick movement. All six of their legs look the same. Water bugs have forelegs adapted to grabbing prey (raptorial legs). Their legs are also adapted for swimming and have no obvious spines.

Cockroaches are usually classified as pests by humans, but some provide important ecosystem services (i.e. they are decomposers) and others are television and movie stars (i.e. Madagascar hissing cockroaches).




Giant water bug
cc-by-nc 4.0 Christian Schwartz

American cockroach
cc-by-nc 2.0 K. Schneider

Contributed by Dr. Meghan Vankosky (@vanbugsky). 

The case of the innocuous versus the evil twin: When making pest management decisions, be sure that the suspect is actually a pest. This can be challenge since insects often mimic each other or look very similar. An insect that looks, moves and acts like a pest may in fact be a look-alike or doppelganger.
Correctly identifying a pest enables selection of the most accurate scouting or monitoring protocol. Identification and monitoring enables the application of economic thresholds. It also enables a producer to select and apply the most effective control option(s) including method and timing of application.  For the rest of the growing season, the Insect of the Week will feature insect crop pests and their doppelgangers.

Doppelgangers may be related (e.g. same genus) or may not be related, as in the case of monarch butterflies (Danaus plexippus) and viceroys (Limenitis achrippus).  Doppelgangers are usually relatively harmless but sometimes the doppelganger is a pest yet their behaviour, lifecycle or hosts may be different.

Review previously featured insects by visiting the Insect of the Week page.

Insect of the Week (Aug 12) - Doppelgangers: Hoverflies vs. bees vs. yellow jacket wasps

Hoverflies are un-BEE-lievably good mimics of bees and yellow jacket wasps!

Mimicry is used by insects in several ways. Some insects, like the ambush bug and praying mantis, look like plants. These predators sit very still, blending into their surroundings, and wait very patiently for their unwitting prey to pass by. Other insects, use mimicry to avoid predation, often by taking on the appearance of species with clear markings that are known to be dangerous. Hoverflies (Diptera: Syrphidae) are some of the most convincing mimics of all of the insects. Even experts can have a difficult time distinguishing hoverflies from bees and wasps, especially when working in the field.

Bees (honeybees, solitary bees, native bees; Hymenoptera: Apidae): Bees are important pollinators, usually with distinctive black and yellow strips. Bees have two pairs of wings and are much fuzzier than wasps or hoverflies. Bees have stingers, but are not aggressive under normal circumstances. Some species of bees (e.g. honeybees) have barbed stingers that become lodged inside their victim. When this happens, the stinger is pulled out of the body of the bee and the bee dies. For this reason, bees with barbed stingers only sting as a last resort, in an effort to protect their colony. Bees are beneficial insects that will leave you alone if you leave them alone.

Honeybee
cc-by 2.0 Renee Grayson

Yellow jacket wasps (Hymenoptera: Vespidae): Yellow jackets and some of their close relatives have colouring similar to bees. Like bees, wasps have two pairs of wings. Unlike bees, which are usually vegetarians, wasps are carnivores that eat other insects. Thus, wasps are beneficial insects, but they also have a bad reputation for harming people because they scavenge for food at our picnics and barbecues during the summer. Wasps also tend to be aggressive and will sting with little provocation.

Yellow jacket wasp
cc-by-nc-nd 2.0 Bryan Jones

Hoverflies (Diptera: Syrphidae): Hoverflies belong to a completely different order of insects than bees and wasps. Like bees, hoverflies are pollinators and are often observed hovering over flowering plants in fields and gardens. Unlike bees and wasps, hoverflies only have one pair of wings. Hoverflies do not have a stinger. They also do not have biting mouthparts, so they can do no harm to people. Hoverflies protect themselves from predators, and people, by mimicking bees and wasps. In addition to pollinating plants, hoverflies provide another important ecosystem service: their larvae are predators of small plant-dwelling insects like aphids!

Syrphid
cc-by-nc-sa 2.0 Eero Sarkkinen

Contributed by Dr. Meghan Vankosky (@vanbugsky). 

The case of the innocuous versus the evil twin: When making pest management decisions, be sure that the suspect is actually a pest. This can be challenge since insects often mimic each other or look very similar. An insect that looks, moves and acts like a pest may in fact be a look-alike or doppelganger.

Doppelgangers may be related (e.g. same genus) or may not be related, as in the case of monarch butterflies (Danaus plexippus) and viceroys (Limenitis achrippus).  Doppelgangers are usually relatively harmless but sometimes the doppelganger is a pest yet their behaviour, lifecycle or hosts may be different.

Correctly identifying a pest enables selection of the most accurate scouting or monitoring protocol. Identification and monitoring enables the application of economic thresholds. It also enables a producer to select and apply the most effective control option(s) including method and timing of application.  For the rest of the growing season, the Insect of the Week will feature insect crop pests and their doppelgangers.

Review previously featured insects by visiting the Insect of the Week page.

Insect of the Week (Jul 29) - Monarch vs. Painted Lady

The case of the Monarch butterfly vs. Painted Lady butterfly (also Viceroy butterfly)

An orange butterfly fluttered by. Was it a Monarch butterfly (Danaus plexippus)? Or a Painted Lady butterfly (Vanessa cardui)? If it’s a Monarch, it is species of Special Concern listed under the Species at Risk Act and is not a crop pest. Instead, it’s larvae feed solely on milkweed (Asclepias spp.), typically found in wetland areas. Painted Lady larvae, on the other hand, feed on a wider range of plants including sunflower, canola, mustard, borage, soybean, Canada thistle, burdock, knapweed, wormwood and many other plant species. While neither species overwinter in Canada, Monarchs have regular migratory routes into Canada from Mexico through the USA; Painted Ladies are accidental tourists that are on occasion blown up from the US.

One important distinguishing characteristic is the distinct black band with white dots that outline the wings of Monarchs. Painted Ladies do not have this band; instead they have thin white markings along the scalloped wing edges.

Monarch butterfly (Danaus plexippus)
cc by sa 3.0 Kenneth Dwain Harrelson

Painted Lady butterfly (Vanessa cardui)
cc by 3.0 Jean-Pol Grandmont

Viceroy butterflies (Limenitis archippus)
cc by 2.0 Benny Mazur

Viceroy butterflies (Limenitis archippus) are even more difficult to tell from Monarchs. Viceroys are smaller than Monarchs and sport a black line running through the middle (side-to-side) of the hindwing. Like the Monarch, Viceroys are not crop pests as their larvae feed exclusively on trees of the willow family (willow, poplar, cottonwood).

For more information about Painted Lady butterflies, see the Insect of the Week page and our posts on the annual Monarch butterfly migration. 

The case of the innocuous versus the evil twin: When making pest management decisions, be sure that the suspect is actually a pest. This can be challenge since insects often mimic each other or look very similar. An insect that looks, moves and acts like a pest may in fact be a look-alike or doppelganger.

Doppelgangers may be related (e.g. same genus) or may not be related, as in the case of monarch butterflies (Danaus plexippus) and viceroys (Limenitis achrippus).  Doppelgangers are usually relatively harmless but sometimes the doppelganger is a pest yet their behaviour, lifecycle or hosts may be different.

Correctly identifying a pest enables selection of the most accurate scouting or monitoring protocol. Identification and monitoring enables the application of economic thresholds. It also enables a producer to select and apply the most effective control option(s) including method and timing of application.  For the rest of the growing season, the Insect of the Week will feature insect crop pests and their doppelgangers.

Review previously featured insects by visiting the Insect of the Week page.

Insect of the Week (July 22): Doppelgangers: Lygus bugs nymphs vs. aphids

The case of lygus bug nymphs versus aphids: Small, green, soft-bodied, sucking insects - at first glance they could be either lygus bug nymphs or aphids. But spend a moment and look for the following characteristics, and you'll be able to tell which pest you are dealing with.

• Size: depending on the species, aphids can reach up to 4 mm long, but most will be 1-2 mm. Lygus bug nymphs will be larger, 4-6 mm long
• Cornicles (small upright backward-pointing tubes found on the back side at the rear of abdomen): aphids have them, lygus bug nymphs do not. In some aphid species, the cornicles or where they attach to the abdomen are black (e.g. corn aphid, English grain aphid). 
• Markings: older lygus bug nymphs have five distinct black dots on their thorax and abdomen; aphids do not.

For more information about these species and more tips on telling them apart, see our Insect of the Week page! Also, see our Monitoring protocols for lygus bugs in canola. 

Tarnished plant bug nymph - note five black dots on

throrax and abdomen - Scott Bauer, USDA



English grain aphid - adult and nymphs - note black cornicles

(tubes) sticking out the back - Tyler Wist, AAFC

The case of the innocuous versus the evil twin: When making pest management decisions, be sure that the suspect is actually a pest. This can be challenge since insects often mimic each other or look very similar. An insect that looks, moves and acts like a pest may in fact be a look-alike or doppelganger.

Doppelgangers may be related (e.g. same genus) or may not be related, as in the case of monarch butterflies (Danaus plexippus) and viceroys (Limenitis achrippus).  Doppelgangers are  usually relatively harmless but sometimes the doppelganger is a pest yet their behaviour, lifecycle or hosts may be different.

Correctly identifying a pest enables selection of the most accurate scouting or monitoring protocol. Identification and monitoring enables the application of economic thresholds. It also enables a producer to select and apply the most effective control option(s) including method and timing of application.  For the rest of the growing season, the Insect of the Week will feature insect crop pests and their doppelgangers.

Review previously featured insects by visiting the Insect of the Week page.

Insect of the Week (July 15): Doppelgangers: Lygus bug vs. Alfalfa plant bug

The case of lygus bug versus the alfalfa plant bug: It is easy to understand why lygus bugs (Lygus spp.) and alfalfa plant bugs (Adelphocoris lineolatus) are difficult to tell apart as they are closely related, belonging to the same family (Hemiptera: Heteroptera). They are similar in appearance (long narrow body) with the alfalfa bug being slightly longer. Adult lygus bugs have a distinctive triangular or "V"-shaped marking in the upper centre of the their backs and membranous wingtips. The alfalfa plant bug has a similar marking but it is less distinct. One difference between the two is that lygus bug nymphs have five black dots over their thorax and abdomen which alfalfa bug nymphs lack.

Another difference is that lygus bugs have a broader host range that includes canola, alfalfa, soybean, sunflower, strawberry and several other crops. Alfalfa bugs have a much more particular palette and are mainly found in alfalfa crops and only occasionally feed on red and yellow sweet clover or canola when alfalfa is in short supply.

For more information about these species and more tips on telling them apart, see our Insect of the Week page!

Tarnished plant bug (Lygus lineolaris) - cc-by Scott Bauer

Alfalfa plant bug (Adelphocoris lineolatus) - (c) Mike Dolinski. MikeDolinski@hotmail.com

The case of the innocuous versus the evil twin: When making pest management decisions, be sure that the suspect is actually a pest. This can be challenge since insects often mimic each other or look very similar. An insect that looks, moves and acts like a pest may in fact be a look-alike or doppelganger.

Doppelgangers may be related (e.g. same genus) or may not be related, as in the case of monarch butterflies (Danaus plexippus) and viceroys (Limenitis achrippus).  Doppelgangers are  usually relatively harmless but sometimes the doppelganger is a pest yet their behaviour, lifecycle or hosts may be different.

Correctly identifying a pest enables selection of the most accurate scouting or monitoring protocol. Identification and monitoring enables the application of economic thresholds. It also enables a producer to select and apply the most effective control option(s) including method and timing of application.  For the rest of the growing season, the Insect of the Week will feature insect crop pests and their doppelgangers.

Review previously featured insects by visiting the Insect of the Week page.

Insect of the Week (July 9) – Doppelgangers: Grasshoppers

Bruner grasshopper (Melanoplus bruneri) adult. 
Photo credit: S. Barkley, Alberta Agriculture and Forestry.

The case of the prairie grasshoppers: There are 80 grasshopper species on the prairies but only a few that are considered pests. These include Packard (Melanopus packardii), clearwinged (Camnula pellucida), migatory (Melanopus sanguinipes), two-striped (Melanopus bivittatus) and Bruner Melanoplus bruneri) grasshoppers. They are recognizable as grasshoppers (similar body shape and distinctive large rear legs) and, depending on the species, range in size from 21 to 40 centimetres (8.25 to 15.75 inches). Most of these pest species can be distinguished by colouring and size. However, the Bruner and migratory grasshoppers are difficult to tell apart, needing to rely on examining the male genitalia (see Insect of the Week post from July , 2018).

For more information about grasshopper pests, see our Insect of the Week page!

Packard grasshopper – egg, nymph, adult

AAFC

Clearwinged grasshopper – egg, nymph, adult

AAFC

Migratory grasshopper – adult

Joseph Berger, Bugwood.org

Two-striped grasshopper – adult

John Gavloski, Manitoba Agriculture,

Food and Rural Development

More information related to the Bruner grasshopper:

-       https://www.sidney.ars.usda.gov/grasshopper/ID_Tools/F_Sheets/brunersp.htm

-      http://scholar.ulethbridge.ca/sites/default/files/danjohnson/files/grasshopper_identification_control_methods.pdf

-       http://www1.agric.gov.ab.ca/$Department/deptdocs.nsf/all/prm16528

See also: Predicted grasshopper development (July 5, 2019)

Specific information about these grasshoppers, other pests and natural enemies can be found in the updated Field Crop and Forage Pests and their Natural enemies in Western Canada field guide.

The case of the innocuous versus the evil twin: When making pest management decisions, be sure that the suspect is actually a pest. This can be challenge since insects often mimic each other or look very similar. An insect that looks, moves and acts like a pest may in fact be a look-alike or doppelganger.

Doppelgangers may be related (e.g. same genus) or may not be related, as in the case of monarch butterflies (Danaus plexippus) and viceroys (Limenitis achrippus).  Doppelgangers are  usually relatively harmless but sometimes the doppelganger is a pest yet their behaviour, lifecycle or hosts may be different.

Correctly identifying a pest enables selection of the most accurate scouting or monitoring protocol. Identification and monitoring enables the application of economic thresholds. It also enables a producer to select and apply the most effective control option(s) including method and timing of application.  For the rest of the growing season, the Insect of the Week will feature insect crop pests and their doppelgangers.

Review previously featured insects by visiting the Insect of the Week page.